Hotjse electbic



Dec. 11, 1923. 1,477,305

- c. T. ALLCUTT DISCHARGE GAP Filed A ril 4, 1919 F29 9v /yz WITNESSES: INVENTOR Patented Dec. 11, 1923.

CHESTER T. ALLCUTT,' OF PITTSBURGH,

PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTUEING'COMPANY, A. CORPORATION OF PENNSYL- VANIA. f

Application aiedn rn 4,

To aZl'whomit-may concern:

Be it known that I, CHns'rnR '1. Anncucrr, a citizenof the United States, and a resident of Pittsburgh, in-the .county of-Allegheny and State of Pennsylvania,- have invented -.a new and useful Improvement in :Discharge Gaps, of which the following is a'specific'ation 311T ,i v .i

My inventionrelates to discharge. aps, .as usedinclightning arrestersfiiandz' it? as for itsobjectto provide apparatus of the 'charaster desi'gnated that shall= have; anlowl .impulse ratio, 'that is to sayitheqratio -of-the potential at which the gapreeks-down with high frequency discharges; the lpotentlal at which the gap Breaks downat normal frequenc is low in value, preferably being conside lyiiless thanl-unit'y. I

: in the iiccompanying diagrammatic view of ce'rtain-e ementscom- I1 posing a gap embodying a preferredform of my invention, t then with. associated load and-discharge circuits 2: :and 2-3 :are similar views: of modifications of "ratus shown in-IFig; *1; Fig. 4- is'a side view, partially diagrammatic,- of .a. ;com mercial form" of apparatus operative in accordance with the system. of Fig. 2 :Figg 5 is asimilar view of another 'form of commercial apparatus 'embodying my invention; and Figs. 6, 7. 8 and 9 are diagrammatic views of still other forms of apparatus.

In the construction and application of discharge gaps for ithe'protection of transmission lines and similar uses; it is desirable that the gap shall not break down at line potential and the normal frequency but that the gap shall break down at as low a voltage as possible .upon the occurrence of abnormal frequencies. such as switching surges and lightning discharges.

In my former application, Serial No. 216,- '088. "filed Feb. 8, 1918, and assigned to the -ll"estinghouse Electric 8:. Manufacturing Company, I disclose apparatus functioning in this manner. an antenna'being disposed between the main discharge electrodes and being connected thereto through impedance devices of dissimilar character, the adjust ment being'such that, at normal frequency, the drops in said impedance devices determine the potential of this antenna at a value substantially the same as that of the immediately adjacent electrostatic field. Upon a Fig; 1.15 a

DIscHARGE GAP.

1919; Serial No. 287,573.

- change in the frequency of the system, the

drops in the two impedance devices change. their relativerat-io so. as to cause the antenna ;to assumes. potential difi'erent from that .-which themain 'electrodesstrive to set up in the field immediately adjacent to the an -.-tenna. Thus, the antenna disturbs the electrostatic-conditions with a'change in the fre- .quency and this'efiect so pronounced asto cause as given gap to ,-break::d0wn .with a high-frequency voltage iiarlowerrthan the gap will hold'atnormal above; in its normal aspects but differs therefrom in-detail. ='1-wo main electrodes are -.-employed' that .have; a somewhat distorted and. non-uniform I electrostatic fieldtherebe- .tween and. which have, preferably an impulse "ratio of substantial unity. For this ,purpose, two spheres maybe-used having a space therebetween considerably exceeding theradius thereof.

One-pr more conducting members are so disposed and connected to the circuit that, at normalr frequency, they serve to largely eradicate the field distortion and concentrations of electrostatic; flux, so that the gap is .enabled to withstand a relatively high voltage diiference at normal frequency. The energizing circuit of the conducting members is so arranged that, upon the occurrence of high frequency, the corrective efi'ect thereof upon the electrostatic field is partially or wholly eliminated, so that currents of abnormal frequency flow freely across the gap, even if of. less than normal line voltage.

Referring to the drawing for a more detailed understanding of my invention, I show a main discharge gap at 3, being formed by discharge electrodes 4 and 5, preferably of spherical contour and spaced .apart more than their respective radii. The electrode 4 may be connected to a line wire 6, and the electrode 5 may be connected to ground at 7 or the discharge gap may be associated with an electrolytic arrester or be otherwise employed, as is well known to those skilled in the art.

A toroidal shaped conducting member 8 is disposed around the electrode 4 and connected thereto through an impedance device 9 embodying either resistance, reactance, or both. Similarly, a toroidal shaped con relquency.'5z. 0 he+-presentp1nventzon is similar to themay becaused tobe tibsehee of the members 8and '10, and the '9. length is such that the ga'p wouldbe ia le to break down at line 'potcntial'or 1es's.'- At norml fr" uency, the device-12 is of xtremely-high impedence and the devices 9 and '11 's'rve'tornsintain the inembers'8 and 10'at si'ibst'antia'lly the potentials of the associated eIect -ode Under these conditions, the corretii're'efiect of 'theine'm bers '8 "and 10 upon thefieldbetween the electrodes '4' ttndf ,fi'isshch ts to substantially retrieve the loci cf stee pot'ehtittlgradiem therefrom, minimizing the liabilit' to breakdown andler'gely increasin theability bf the gap to i'witlisttnd potehtia'l, Under these 'conditioiisihe@ttliisfiiintn a setting fer less then w tntl 'Eie "permissible "in "the absence tat tnemmbers's snu 10. 'Upo'h'the'becurfenceofabhormal fieqtiefl j the im edsnte at tne'uevreese and 'Ilrefnainscbiistent if these 'niehiber's ar'e -fiu'rly ohmic resistant-e ihd largel inettttses ifftne's ifien ibersitmstars 13 and 14' decreases to a marked erltent body reactance while the 'i'fflfledeifiee'bfthe "nest 12 "Beer sets. 'Th'ns, the "potentialdetrihi'nin'gTu tibh artne'mtmbeis'eftmd '1'1 11" on the 'ttembtts, s we 1;0 decreases, pens din t e'me'mbts 8"in'd 10th more may f om he potentialf'oftheir immedititely ttssotiat d (elements. 'At the same time, the "relatively 'lofiv inttseae'fise oif'the deiri'ce 12 tense the tt tst 'sthiettch 1 other in ot'ntial, "tending twttss'u'tnet set ntiall'interm'edidtwbetween those Yet the di charge electrodes. I 'n'der these donditio'n's, the tentative 'fict'fof' the "members "a and 10 "u "an the "electrostatic fieldis 'l'tirg'efy reducedij'aer'mittirig the gap 'btti 'e n the "electrodes and "5 to 'break two potential-ttdji'jsti'1'1" members. Thus, in the gge shown n ig. *2, the discharge so high that 'performs the inth-e device "of Fig. 2, and the electrolytic 'tiode 4 is disposed opposite'an its before, the latter electrode'be'in g g'rounded through an" electrolytic"arrester 15. 'At' im pedence device 9 and being connected to ground through a condensiye reactor 12.

The operation of thestructure thus'shown will be obvious from a consideration of the discussion of 1.

Referrirw to the "form 'jofiny intention shown in ii'g. 3,the'discifeirgeelectrodes snd guard rings are as before, sisere also the connecting devices 9 and 11.

The guard ring 8 is connected to the discharge electrode 5, however, through a condenser 13 and, similarly, the*guard rii't 10 is connected to the discharge electro e 4 through a condenser 14. The devices 9 and '11 may embody either p ure ohmic "resistance or resistance and inductance, as desired and as dictated 'by the particular design considerations.

In operation, at normal frequency, the impedance (if the condensers 1'3 and 1'4 is the guard rings 8 t'rndElO are charged 'to substantially 'the potential of their i mn'ie'diately ad]'ecent discharge electrodes, as previously set forth, thus exerting the desired corrective'efiect on the 'distorted' electric field tenlding to beesteblished by theelectrodes 4 and 5..

Upon the occurrence of an abnormal rise in frequency, the-impedance of the members 9"and '11 remains constant, if3thest= members ereipilre ohmic resistanceyand-rises if "these me'm ersferhbody reactance. 'At the same'time, the"realctan ce of theco'ndenjeorre ct the same, and a quick and effective break-doWn is secured.

Referring to Fig. 4,-a discharge electrode 45 is disposed opposite the electrode "5 in such 'mannernstonorm ally tend to produce "a'badly"distortedfield. Theelectrode 5 is connected to ground,"as' throu'ghhn electrolytic lightliing nrrester 15. The guard 'ri'n 8 surr'ounds theelectrode 4t ztnd isconnected thereto"through an impedance device 9, 'as

previously described. Tho -guard" ring 8 is mounted on an insulator-lfi'havihg'wgrounded "metallic pin 17 Under these conditidhs, the insult'itor 16 function ofthe condenser 12 charge o'fline energy across the gap after the abnormal frequency disturbance has been 're'ndoyed.

'I'n theepparatusshovn in'Fig. 5, an elecelectrode' 5,

giiard device of Fig. 4. The ring 8 carries a born 18, and the electrode 5 carries an opposing horn 19.

The electrode 4 is carried by a shank 20 supported from an insulator 21 and a charging resistor, shown as of the stick type, is shown at 22. An inductive connection 23 joins the resistor 22 with the guard ring 8.

In the operation of the device thus shown, the member 22 serves as a charging resistor for charging the arrester 15, the gap between the horns 18 and 19 being temporarily bridged by any suitable apparatus. Dis-. turbances of normal frequency but of high volta e take lace between the guard ring 8 and t e member 5 and are extinguished by the joint action of the arrester 15, of the resistor 22 and of the horn gap l8-19.

Disturbances of abnormal frequencyuso disturb the potential ofthe 'uard ring 8, because of the inductance of the member 23 and the capacitance of the member 16, that a discharge is initiated between the electrodes 4 and 5.

.With the variousforms of apparatus discussed to this point, the guard ring is, at times, of appreciably different potential than its associated discharge electrode, the potential difierence with abnormal frequency'possibly rising to as great a value as thepoten- -tial across the gap itself. This necessitates disposing the guard ring at such distance from the'discharge electrode asto materially reduce its field-controlling function.

Referring to the form of apparatus shown in Fig. 6, means are shown for materially correcting this effect. A discharge electrode 4 is disposed opposite the ground electrode 5, and a guard ring 8 surrounds the electrode 4, as before. An impedance mem1 ber 25, either inductive or noninductive, is connected between the lead to the electrode 4 and ground through a condenser 26. An intermediate point in the element 25 is connected to the guard ring 8.

Under these conditions, the impedance of the device 26 is very high, at normal frequencyyand that of the device 25 is relatively low, so that the guard ring 8 approximates the electrode 4 in potential. Uponthe occurrence of a discharge of abnormal frequency, the impedance of the device 26 is relatively small, whereas that of the device 25 becomes relatively large, the device 25. in effect, being connected between line and ground. Under these conditions, the potential of the guard ring 8 is intermediate between that of the line and that of ground. the particular value being determined by the point of attachment of the guard ring to the element 25.

In the form of apparatus shown in Fig. 7, guard rings 28 and 29 are associated with the discharge electrode 4 and this electrode is connected to ground through impedance devices 30, 31 and 32. The devices 30 and 31 may embody pure resistance or resistance and inductive reactance, whereas the device embodies condensive reactance.

At normal frequencies, both of the guard rings are at substantially the potential of the dischar e electrode and exert a pronounced fiefil-correcting eilect. Upon the occurrence of abnormal frequency, the guard ring 29 assumes substantially ground potential but, by reason of its large size, and consequent spacing from the electrode 4, this does not lead to undesirable discharges. The intermediate guard rin 28, by reason of its closer spacing from t e electrode 4, is in greater dan er of discharge therefrom but the potential of this ard ring, during ab normal frequency, is xed by attachment between the elements 30 and 31 as is the potential of the guard ring 8 in Fig. 6.

Another form of apparatus -for protecting the guard ringfrom undesiredfidischarges is shown in Fig. 8. The discharge. electrode 4 is connected to ground through condensers 33 and 34, and the condenser 33 is shunted by an impedance device 35, embodying either pure resistance or resistance and inductive reactance. At normal frequency, the condensers 33 and 34 rform little or-no action and the potential of-the ring 8 isv substantially that of the electrode 4 because of the connection through the impedance device 35. With abnormally high frequency, the element 35 may be-disregarded and'the potential of the guard ring '8 is determined by the relative magnitudes of the condensers 33 and 34, the guard ring being connected therebetween. V

Still another form of myinvention is shown in Fig. 9 in which the ring 8 iscon- 'nected to the discharge members. 4 and 5 by means of condensers 36 and 3?, respectively, which serve to maintain the ring 8 at the desired potential with. .respect to the electrodes 4 and 5 during normal. conditions but which are of insutlicient capacity to carry a discharge current. The ring 8 is also connected to the discharge member 4 through an auxiliary spark gap 38, which. being of a high impulse ratio, willbreak down at a slight over-voltage of normal frcuency, bringing said ring to substantially t e potential of the electrode 4 and preventing a main gap discharge until a considerably higher voltage has been reached. On the other hand, a high-frequency over vo1tage will discharge across the main gap before breakingidown the auxiliary gap and at a lower voltage than a normal-frequency over voltage, on account of their respective impulse ratios.

Throughout this specification, I have disclosed guard members of toroidal shape, as, under most operating conditions, this is the most effective form of device but, obviously,

a 'pa'f'ti'al toroid -or guard ring or mem er "of'niany other shapes would function in 'a similar ihanne'r although, generally speaking, to a lesser degree.

"Furthermore, in many relations where l havesho'wn a condenser, the inherent condensance between adjacent conducting elements is suflicient to perform the desired function and,thus, in many cases. the condensers'slzon'n' may be considered merci r illustrative andmay be omitted in the actual "construction ofthe device.

It will 'benoted th'at the device of Fig. 3 causes the development of a greater voltage between imam ring and the associate elec- 'trode under high-frequency conditions than doesthe'strucuire of Fig. 1, nherens, the 'dei ic'eof Figs, 6, 7 'and 8 provides 'for the establishmento'f lesser volt-ages than are developed in the system of F '1 "under simi larconditions. The particular designto be followed depends largely upon design considerations, such, for "example, as operating olta dand 'the'raidii "of the' 'curvature of 'tlieelect-rodes l'an d 5 and df the respective guard rings. "1 show these different :forms ofstfiucture so as toillnstra tetheivide flexibility of designthat is possible under the fundamental principles lierein "sctforth. and to emphasize the wide adaptability of the pre'slent'structure in 'the protecti on of "transmission lines from undesired high-frequency impulses. I i While I have 'shon'rn my-invention 1n a pluralit of "forms, it 'will be obiiious to those skilled'in the art that it is not solunited but "is susceptible of various minor changes and modifications without departing from the "spirit thereof and Id'sue. therefore, that only 'such limitations shall be placedthereuponns are imposedby the prior art or are specificallysetforth 1n the appended claims. I

'I claim as my invention:

1. In electrical-discharge-gap apparatus, the combination with two discharge members mounted in spaced relation to each other, of 'nielanssurrounding one of said discharge members but spaced therefrom and adapted to prevent distortion of the electrostatic field between said discharge members at normal frequency of said circuit and to permitthe distortion thereofat othr tha'n normal frequency.

2.In electrical-discharge gal) apparatus, the combination with two discharge members mounted in spaced relation to each other, "of an auxiliary electrode surrounding one of said discharge members'but spaced therefrom, "and connections embodying imedance members of dissimilar character between said auxiliary electrode and said "discharge members, respectively. said connections having impe'd'ances, at the normal frequency of said circuit, substantially pr0- "other; of "aukiliary toroidal portion'al'tothe distance between said auxiliary electrode and said discharge members, respectively.

3. In electrical-discharge-gap "apparatus, the combination with two discharge members mounted in spaced relation to each othezg'of'an auxiliary electrode mounted adjacent eachjof'said discharge members and connected thereto and to each other'by means of connections havingiimpe'dances of dissimilar impedance'character.

4. In an electrical-discharge-gap apparatus, the combination with two discharge members mounted in spaced-relation to each other, of an auxiliary toroidal "shaped "electrodemounted to su'rro'uhd one of said disch arge meinber's "in'spaced relation, and connections between said auxiliary electrode and said discharge 'niembers, one "of which embodies 'non-'capacitative im edan'ce' and "the-"other of *w'hich'embd'di's p'acitance.

'5. -"I'n '.'el'ectricaldischarge gap cap ratus, -the combination viithtwo disc *iriembers mounted in spaced relation to each other; of auxilia "electrodes mounted! adj'ac'entjiea'ch'of 'Hischarge *illembefsfconnectionsbetweemeilchofsaid'anxiliarreictro'des and the adjacent discharge members embodyingimpedance axltln connection 'between Said auitiliary electrodes embodying impedance of "a'nature dissimilar to that previouslymentioned.

. 6. Inelectriciil dischargegaPapparatus,

the combination 'With two- 'isclrirge"members' mounted, iii spaced relation t'o ach- "otlienmf ad rilinrry electrodes mo'lmte'd adjacenteachof said discharge inembrsmonnctlon's between eachofsaid' air'xiliziry electrodes and 'the adjacent discharge "inmber embodyinir'nomcapacitative impedance, =ahd a connection 'between said aui'rlliary' electrbdesehbodyrig capacitance.

7. In "lectrichl-discharge=gap apparatus, the combination withtwodischar members mounted in spaced relation to each electrodes mbuhte'd'to surround 'each "of said discharge members, connections between each of said auxiliary electrodes and 'the adfacent'dis- "charge 'meniber embodyin non-capacitativ'e impedance, and'aconnec ion between said alixili'ary" electrodes "embodying capacitance. 8." In electrical-'discharge' gap apparatus, the "combination 'with 'twoi'diseharge '-I'r1mniounted in spaced lelation"to -each other, *of "auziilia toroidal electrodes mounted to s'urroun each of said'idi'scharge n'lembers, connections'betweeh' each of 'said 7 ahxiliary electrodes "a'nd the adjacent discharge member "embodying resistance and reactance, and a connection between said aux i] i cr electrodesembodying' capacitance.

'9. In 'electrical-diseharge' fiap "apparatus,

"the "combination ivith two "discharge mem- "hers mounted in spaced relation to each other, of auxiliary toroidal electrodes mounted to surround each of said discharge members, and connections between each of said auxiliary-electrodesand the adjacent discharge member embodying non-capaci tative impedance.

10. In--electrical-discharge ga apparatus, the combination with two disc arge members mounted in spaced relation to each other, of auxilia toroidal electrodes mounted to surroun each of said discharge members, connections between each of said auxiliary electrodes and the adjacent discharge member and between the two auxiliary electrodes embodying impedances, said impedances bein of such value that the auxiliary electro es are maintained at substantially the potential of the discharge member the surround at normal uency of the supply circuit, and are charg at a potential different from that of the discharge member they surround at other frequencies of the supply circuit.

11. In electrical-dischargea apparatus, the combination with two disc arge members mounted in spaced relation to each other, of auxiliary toroidal electrodes mounted to surround each of said dischar e members, connections between each of said auxiliary electrodes and the adjacent discharge member and between the two auxiliary electrodes embodying impedances, said impedances bein of such value that the auxiliary electro as are maintained at substantially the potential of the discharge members they surround at normal frequency of the supply circuit, and are of substantially equal potential at relatively greater frequencies of the supply circuit.

12. The combination with a discharge device provided with a gap and having discharge members so arranged as to tend to roduce a distorted electrostatic field there- Eetween, of a conducting member disposed adjacent said device and connected to one of said discharge members through impedance means that change in effective impedance with changes in the frequency impressed upon said device, whereby the modifying action of said conducting member upon the electrostatic field of said gap changes with changes in said frequency.

13. The combination with a discharge device provided with a gap and having discharge members so arranged as to tend to produce a distorted electrostatic field therebetween, of a conducting member disposed adjacent said device and connected to the circuit thereof through impedance means that change in effective impedance with changes in the frequency impressed upon said device, whereby the modifying action of said conducting member upon the electrostatic field of said gap changes with changes in said frequency, said connecting means and charge ing isc ar e electrodes so arranged as to tend to produce a distorted eletrostatic field therebetween, an antenn member so disposed with relation to said gap as to substantially correct said field distortion if energized to a predetermined potential, and

connectin means embodying reactance between sai antenna member and the circuit of said gap providing means, said reactance being such t at, at normal frequency of said source, said antenna member is charged for the correction of said eld an at ot er frequencies, said antenna member is improperly char d to produce this effect.

15. In a discharge-gap apparatus, the combination with means providing a gap having a distorted field, of means for correcting said distortion at a predetermined frequency, said corrective means bein substantially inefi'ective at materially di erent frequencies.

16. The method of operating a discharge gap to discharge potentials of other than a desired frequency and to prevent the discharge of potentials of said frequency which comprises tending to maintain a distorted field in said ga eliminating said distortion at said desire frequency and permitting said distortion at other frequencies.

17. In electrical-discharge-gap apparatus,

roperl the combination with two discharge members mounted in spaced relation to each other, of means for preventing distortion of the electrostatic field between said discharge members at normal frequency of said circuit and to permit the distortion thereof at other than normal frequency.

18. In combination, a discharge p comprising two spaced electrodes, an a substantially ring-shape member surrounding one of said electrodes, and an electrical connection between said member and the electrode which it surrounds comprising impedance.

19. In combination, a discharge ap comprising two spaced electrodes, an a substantially ring-shape member composed of electrical-current-conducting material surap connected thereto' and embody rounding each of said electrodes and spaced 21. In combination, a discharge gap com-h rounds said ring-shape membm's being OD. prising twprspaoed. electrodes, and; a subnectedxtogether. electrically. stantially ring-shape member compgsed.oi lmtestlmonyfi whet-69f; Ix hayahhpnemtoh electrical current conducting material sursubscribed my; name this, 24.};hhday of; 5 roundjngeach of said elwbmdes, each. of March, 1919;

said: ring-shape. members. bein .,ele otl'ically. connected to, the electrodaw -ich it syn QHE-SLHEfiEv- Ja aQUZFTL 

